Advice at an early stage

To make the most of our experience and to maximise the benefit from Harland’s involvement we can advise on a site’s suitability for ground stabilisation at an early stage – preferably after completion of the initial site investigation.

 

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Benefits of prior extraction before
development by ground stabilisation

  • Once the coal voids/seams have been removed there is 100% confidence in ground conditions
  • The overburden is replaced in 250 mm layers, engineered by compacting to NHBC standards, validated by others and can be left at development platform level
  • Any mineshafts can be capped at depth, removing the need for any exclusion areas at surface, enabling more area for development
  • Exposed old mineworkings exposed in the boundaries of the site development area, will be clay sealed, in line with the requirements of the coal authority, ensuring no gas ingress into the development area
  • The tonnage recoverable ranges from 500 tonnes upwards. The coal having to be removed from site and disposed of, as it is a combustible material and unsuitable to be sent to a normal landfill
  • Typical site duration for a 6,000 tonne site is 10/12 weeks including earthworks
  • Typical site duration for a 30,000 tonne site, coal only, 14 weeks

Make the most of our experience

  • Alternative methods of ground stabilisation, such as grouting, are a financial outgoing.
  • Dependant on recoverable tonnage, prior extraction could in some cases be the most economical method of ground stabilisation of old mineworkings and coal seams within the development horizon. The overburden contract being let as a separate contract.
  • Each site is evaluated on its individual merits.